Synopsis... any lingering showers at sunrise over Cape Cod and the islands will move offshore and give way to a dry warm Sunday afternoon behind a departing cold front. A secondary trailing cold front may result in a few showers tonight into Monday. Otherwise, an extended period of dry weather is expected beginning Tuesday and likely continuing into next weekend as Canadian high pressure crests across the region. The high will initially be accompanied by unseasonably cool weather Tuesday into Thursday morning. A gradual warmup is expected with temperatures possibly rebounding into the 80s Friday and Saturday.

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Near term /until 6 PM this evening/...

Scattered showers remain across the southern waters, with the northern fringe sneaking into the islands early this morning. The approaching cold front, extending from western Maine to western Massachusetts into northern Delaware early this morning will continue to slowly cross the region today, but it will remain dry. The front finally reaches the southern waters this evening before stalling near or south of Long Island as the front becomes nearly parallel to the zonal mid level steering flow.

Noting the low clouds associated with the front have push to southern areas, mainly along the S coast and the adjacent coastal waters. However, with the briefly clearing skies, light winds and low T/TD spreads, there are areas of low stratus clouds as well as areas of fog which are locally dense away from the coast at 08z. Should see the fog burn off rather quickly with the mainly clear skies above the stratus, though some fog may linger across portions of Cape Cod and the islands through around midday.

With west-northwest winds in place behind the exiting front, temps will rebound nicely across the region. 850 mb temps will range from +8c across NE mass to +11c across north central CT this afternoon. This should translate to highs reaching the mid 70s to around 80. Readings may be a bit cooler along the S coast as winds remain from the SW. Clouds will start to move into northern mass during this afternoon ahead of the next approaching system.

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Short term /6 PM this evening through 6 PM Monday/...

Tonight and Sunday...

The nearly zonal 500 mb flow across the region will allow moisture from approaching low pres out of New York state to move in. 00z guidance giving a strong signal of this low as it shifts east-southeast overnight into Sunday. With this system coming from moisture starved inland areas, may not see much precip. Pwats may rise up to 1.3 to 1.4 inches by Monday afternoon across southern areas, but not expecting much in the way of quantitative precipitation forecast. May see around 0.1 inches, maybe a bit higher across western areas closer to the passing low. Expect the precip to push S of the Mass Pike during the afternoon, but should weaken as it shifts toward the S coast late in the day.

Temps should fall back to the 50s to around 60 tonight, mildest along the S coast, with highs on Monday in the upper 60s to around 70.

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Long term /Monday night through Saturday/... updated 340 am ...

Highlights...

* an extended period of dry weather is likely Tuesday thru Saturday * fall-like Tue/Wed with highs only in the 60s and lows in the 40s * Summer-like warmth possible Fri and Sat with highs in the 80s

Precipitation ...

Looks like an extended period of dry weather as high amplitude pattern evolves with deep closed mid level low over the northwest Atlantic along with upstream 588 Dam Ridge from the MS valley into the Great Lakes. This setup supports dry northwest flow into New England. Thus dry weather should prevail Tue thru Sat per ensembles and deterministic guidance. Definitely a pleasant stretch of weather.

Temperatures ...

Very pleasant Fall-like weather this period featuring mild days and cool nights. Cooler air begins to advect into the region Monday night into Tue as trailing short wave energy dives into the base of maritime trough. Ec ensembles have core of cool air centered over eastern Massachusetts Wed into Thu morning with 850 mb temps down to only +3c! This will translate to highs only in the 60s Tue and Wed despite plenty of sunshine. Normal high this time of year is 70-75. Lows will be mainly in the 40s, low 50s in the urban areas. As 588 Dam Ridge over the Ohio Valley builds eastward into New England expect a noticeable warmup with Summer-like warmth possible Fri and Sat as highs likely climb into the 80s with ec ensembles offering +15c at 850 mb. Given 1025+ mb Canadian high pressure over the region much of next week, weak pgradient/light winds and dry airmass will support radiational cooling. Thus will lean toward the cooler MOS nighttime temps. Light pgradient will also support afternoon seabreezes.

Tropical Storm Humberto ...

Good model agreement that Humberto will track away from the East Coast next week and then possibly impact Bermuda around Thursday. Thereafter the European model (ecmwf) continues its theme of anomalous western Atlantic trough capturing Humberto and lifting the tropical cyclone northward across eastern Georges Bank and towards Nova Scotia Fri/Sat. While this track is still southeast of New England it's close enough to watch closely. At the very least this track would yield large swells for Massachusetts/Rhode Island waters and with temps likely warming into the 80s Fri/Sat, rough surf and strong rip currents could be a concern for ocean exposed beaches. The European model (ecmwf) solution is a low probability but will have to be watched given other ec ensemble members support the operational run.

Through 12z... areas of MVFR-IFR ceilings/vsbys, with local LIFR conditions will linger through the remainder of the night. Noting areas of VFR conditions across NE interior mass as well as the mid and lower CT valley, but conditions will vary with the lingering low clouds and patchy fog there. May slowly improve across north central/NE mass after 09z. SW winds 5-10 kt with some gusts to around 15-20 kt across S Rhode Island/S coastal mass terminals, which are beginning to shift to west-northwest across the Berkshires as well as higher terrain such as Worcester.

Today... MVFR-IFR conditions may linger along the S coast as well as the southern islands and coastal waters through a good portion of the day. A few showers and patchy fog may linger across portions of the mid and Outer Cape as well as Nantucket through most of the day. Otherwise, inland fog should lift with conditions improving to VFR by mid to late morning. West-northwest winds at 5-10 kt, though holding from the SW across Cape Cod and the islands through most of the day.

Tonight... clouds increase from northwest-southeast during the night as another weak system approaches. Mainly VFR conditions, but may see local MVFR in any showers or patchy fog. MVFR-IFR visibilities through around 05z in patchy fog across Cape Cod and the islands. Scattered showers may push into into north central and northwest mass after 06z with the next system. Light west-northwest or calm winds.

Monday... mainly VFR conditions. May see brief, local MVFR in any showers, but should weaken as they move S during the afternoon. Light northerly winds early, becoming northwest 5-10 kt during the afternoon.

Winds to diminish after frontal passage this morning, though will stall along the S coast or across the coastal waters by this evening. Expect west winds up to about 10 kt on the eastern waters, but light west-SW winds on the southern waters. Mainly good visibility, but low clouds/fog may linger across the waters near the mid and Outer Cape with visibility restrictions. Seas 4 ft or less.

Dry conditions across the waters tonight. West wind 10 kt or less shift to north toward daybreak. Visibility restrictions linger early tonight across the southern waters to the waters east of Cape Cod, but should improve by 05z-06z. May see local visibility restrictions as scattered showers move into the eastern waters by daybreak. Seas 3 ft or less.

On Monday, area of showers moves across the region rather quickly, weakening as they push off the S coast late in the day. May see local visibility restrictions in the showers. North winds at 10 kt or less become light/variable during the afternoon. Seas 3 ft or less.